Opioids are the most widely used drugs for the treatment of moderate to severe, chronic pain. They achieve antinociception by activation of mu (MOR-1), kappa (KOR-1), and delta (DOR-1) opioid receptors. Natural products found in kratom plant, Mitragyna speciosa, represent diverse chemical groups with opioid activity, providing opportunities to better understand opioid pharmacology. Pharmacology studies show that Mitragynine pseudoindoxyl is a mu agonist/delta antagonist opioid with a signaling bias for G-protein-mediated signaling pathways in vitro and which produced potent antinociception in vivo. Respiratory depression assays along with other behavioral testing also showed that some of the major problems of opioid therapy (physical dependence, respiratory depression, GI transit inhibition) were not observed by the use of Mitragynine pseudoindoxyl in mouse models. In silico docking studies will be carried out to unravel potential differences in receptor interactions with lead compounds.